"People who speak in metaphors should shampoo my crotch"

This quote by Jack Nicholson is an amusing means of expressing his antipathy for individuals who use metaphors. He is recommending that individuals that make use of allegories should be penalized by needing to shampoo his crotch. This can be taken a metaphor for being punished for speaking in allegories, as shampooing a person's crotch is an undesirable job. It could additionally be interpreted as an actual statement, suggesting that Jack Nicholson want to physically punish people that utilize metaphors.

Generally, this quote is a funny means of sharing Jack Nicholson's abhorrence for individuals that use allegories. It is a lighthearted way of revealing his viewpoint, and it is likely that he does not in fact expect people to hair shampoo his crotch as a penalty.